Key duplicating machines for flat keys with lateral bitting are known. They are usually provided with two clamps, one facing a mechanical feeler and intended to clamp the original key to be duplicated, and one facing the milling cutter and intended to clamp the blank key to be bitted. To achieve correct reproduction of the bitting pattern on the blank key, the original key and the blank key, and hence the respective clamps, must be precisely aligned longitudinally.
In particular, clamps are known with two superposed jaws of square plan and with their facing surfaces suitably shaped to be able to retain between them keys of different shapes. In particular, to securely retain a key, the clamp jaws present ribs designed to penetrate into the longitudinal grooves generally present in the key shank.
To overcome the fact that keys present profiles of many shapes, all mutually different, the jaws are formed such as to present a different shape on each of its faces, such that by suitably choosing and positioning the two jaws facing the milling cutter and feeler, the same clamp can be adapted to several different key profiles.
In greater detail, according to the traditional art, the clamp jaws are mounted on a vertical pin fixed to a support mounted on a structure movable in the machine directions X and Y relative to its base, to which the milling cutter and feeler are fixed; in particular, the jaws are mounted on said pin such as to enable each jaw to be rotated about the other and about their support. Correct positioning of the clamp lower jaw relative to its support is generally achieved by vertical pegs rigid with the support and engaging in corresponding holes provided in the lower jaw. The drawback of this solution is that the jaw is rather laborious to construct and is difficult to engagement on the support pegs.
A solution has been proposed involving the presence of a rocker plate positioned on the face of the lower jaw opposite the clamping face and acting such as to urge the jaw against the vertical pin, to which it is connected together with the upper jaw. This solution enables inevitable slack and manufacturing tolerances to be eliminated and ensures that the jaws are disposed with their surfaces always perfectly perpendicular to the milling cutter and feeler axes for any position into which they are rotated about their support. However, apart from the laborious construction of this solution, it requires the use of both hands to rotate the jaw, one hand being used to raise and reposition the jaws, while the other operates the rocker plate.
U.S. Pat. No. 2,282,165 relates to a key duplicating machine in which the base of the lower jaw, of square plan, is provided with grooves which extend cross-shaped from a central hole and are intended to come into contact with projections, also of cross-shape, defined on the upper surface of the clamp support. In particular, the lower jaw can be locked in each of the four angular operative positions by simply rotating the jaw such that its grooves engage different projections on the support.